Here are pics of the various headers that were used in this particular test.
EMC headers – 1.750” X 1.875” stepped tubes with 3” merge collectors.
Chrome drag car chassis headers – 1.750” tubes with 3½” collectors. Tested with 6” longer 3½” diameter collector extensions and also with 27” longer 3½” diameter collector extensions.
Upswept dragster headers – 2” tubes with 3½” collectors
Sanderson truck headers – 1½” diameter short length tubes with 2.375” collector openings.
Fenderwell headers – Circle Track specials, 1.750” diameter & long tubes with 4” collectors.
Fenderwell headers – Drag car specials, 1.625” diameter & long tubes with 3” collectors

Lorena, Texas (South of Waco)